Due to the spread of a multi-core CPU (Central Processing Unit) and a large capacity memory, a multi-system computer configuration mounting a plurality of data processing systems (hereinafter referred to simply as systems) including an OS (Operating System) and an application program (hereinafter referred to as an application) in one computer has been widely used.
Increased degree of integration of the systems in the computer leads to a large range of the influence upon the occurrence of a fault, and a technology detecting the fault and performing a system switching for each system has been developed.
For example, in Patent Literature 1, the technology below is disclosed.
A first OS performing a normal task and a second OS that differs from the first OS are provided, and the second OS captures the sign of a fault by analyzing the content of information held in the first OS.
Then, the second OS makes the process of the first OS to be taken over by the other computer by conveying the analyzed content to the other computer.
Further, for example, in the Patent Literature 2, the technology below is disclosed.
A monitoring means to monitor an execution state of a program operating on a first OS is provided, and when the sign of a fault is detected, the monitoring means notifies a logical computer management means operating on a second OS.
Then, the logical computer management means enables the process to continue by newly activating a third OS which takes over the process of the first OS.
Further, in Patent Literature 3, the technology below is disclosed.
A multi-system computer collecting virtual computers which corresponds to a plurality of single system computers is prepared, and when a fault occurs in any of the single system computers, one of the virtual computers on the multi-system computer realizes continuous processing by taking over the process.
On the other hand, for a system switching apparatus provided against a fault of a system which controls physical equipment such as a motor and the like, the technology below exists.
In order to prevent an unstable control caused by emitting control signals from a plurality of systems, the system switching apparatus performs an exclusive control so that, among an active system actually controlling the equipment and a standby system provided against the fault, only the active system can output the control signal.
For example, in Patent Literature 4, the technology below is disclosed.
A unit transmitting a control signal to an actuator is duplexed, and a master-slave selective module installed outside of the units determines states of an active system unit and a standby system unit at high speed
When the active system unit is abnormal, the normal standby system unit is switched to become an active system, and only the active system outputs the control signal. Then, both systems receive a response to the control signal.